The present invention relates to a three-dimensional air bag for a vehicle. More particularly, the present invention relates to a three-dimensional air bag that can easily be made by joining a plurality of sections together, and is useful for protecting the passengers in a motor vehicle.
A three-dimensional air bag 12 according to the prior art is shown in FIGS. 1A and 1B. When inflated, the air bag 12 has a closed substantially rectangular shape. The air bag 12 has a rectangular base wall 14, an upper wall 16, a lower wall 18, a front wall 17, and a pair of side walls 20 and 22. The side walls 20 and 22 have an enlarged area adjacent the front wall 17, as shown in FIG. 1B.
The air bag 12 is assembled by sewing three panels together along their edges. The three panels include a main panel 24, which forms the base wall 14, upper wall 16, front wall 17 and lower wall 18, and a pair of side panels 26 and 28, which form the side walls 20 and 22, respectively, as shown in FIG. 1A. The main panel 24 has an air inlet 15 and a plurality of attaching holes 31. Each side panel 26 and 28 has a vent hole 27. There are three reinforcing cloth pieces sewn on the main panel 24. A first reinforcing cloth piece 30 is secured adjacent the air inlet 15. A pair of second reinforcing cloth pieces 32 are secured adjacent the end portions of the main panel 24, as shown in FIG. 1A. Each of the side panels 26 and 28 has a third reinforcing cloth piece 34 sewn thereto opposite the enlarged area, as shown in FIG. 1A. The air bag 12 has a total of five reinforcing cloth pieces.
The air bag 12, however, has numerous fabrication drawbacks. First, after fastening one of the side panels 26 or 28 to the main panel 24, it is necessary to manually adjust the position of the other side panel 26 or 28 to ensure the accurate positioning before fastening to the main panel 24. Therefore, it is essential to feed the bag manually through a sewing machine. As such, it is difficult to fabricate the air bag 12 by an automated process including the mechanical feeding of the work. Second, the air bag 12 requires at least three panels 24, 26 and 28. Third, the panels can be prepared only at a relatively low yield with a large waste of material, since the main panel 24 is by far greater in length than the side panels 26 and 28. Fourth, the fastening of the reinforcing cloth pieces 30, 32 and 34 is both labor and time intensive, since at least one reinforcing piece has to be fastened to each panel 24, 26 or 28 adjacent the base wall 14.
It is an object of the present invention to provide an airbag that overcomes the above-identified deficiencies.
It is an object of this invention to provide a three-dimensional air bag for a vehicle which can easily be made by an automatic process including the mechanical feeding of the work.
It is another object of the present invention to provide an airbag having an assembly therein for controlling the flow of air within the airbag during inflation.
It is another object of the present invention to provide an airbag having an assembly for controlling the inflation of the airbag.
The present invention is directed to an air bag formed by a main panel having an air inlet and a subpanel joined to the main panel. The main panel has a pair of first portions that are symmetric to each other with respect to the boundary located adjacent to the air inlet, and a pair of second portions extending in opposite directions from the first portions respectively. The subpanel has a shape identical to the combined shape of the second portions of the main panel, each of the first portions of the main panel have a pair of edges extending from the boundary to one of the second portions. The first portions being joined to each other along the edges adjoining each other to form with the second portions a hollow body having an opening at the front end remote from the air inlet. The subpanel being joined to the second portions of the main panel along their edges to close the opening.
In accordance with the present invention, the main panel has the first portions joined to each other along the adjoining edges, and is joined to the subpanel along the edges of the second portions and the edge of the subpanel. There is no overlapping portion between the joint between the first portions of the main panel and the joint between the main panel and the subpanel. With the present arrangement, there is no necessity to manually remove any panel to avoid any wrong joining when forming any such joint. Therefore, it is easy to employ an automatic sewing process including the mechanical feeding of the work for joining the panels, or panel portions, to make the air bag of this invention. It was possible to make any known air bag by an automatic sewing process involving the vertical motions of a needle.
The air bag according to the present invention has a smaller number of component parts. It essentially consists of only two panels, while at least three panels are required for forming any known air bag. The panels forming the air bag of this invention can be prepared at an improved yield. The main panel is relatively small in length, as the front wall of the air bag is formed by the subpanel. Moreover, it is sufficient to apply a single piece of reinforcing cloth to the main panel, since the main panel forms both a base wall surrounding the air inlet and the whole area surrounding the base wall. No reinforcing cloth is required for the subpanel. Thus, the air bag of this invention has a still smaller number of component parts and requires only a still smaller amount of time and labor for its fabrication.
The air bag according to the present invention may further include a tether having a pair of transverse edges secured to the base and front walls. The tether is adapted to divide the interior into an upper and a lower chamber upon inflation of the air bag. The tether is preferably sized to have a larger spacing on one side of the air bag. The tether as described prevents any undesirably heavy downward load from bearing upon any intefering object below the expanding lower compartment of the inflated air bag even after it has been fully stretched. More specifically, the tether preferably has along its edge secured to the front wall a width substantially equal to that of the air bag as inflated, and is partly cut away along its edge facing the exterior of the vehicle toward the air inlet of the air bag. Moreover, the tether preferably occupies an area of 50% to 80% in the plane in which it extends in the air bag as inflated.
According to another aspect of this invention, there is provided an air bag for an air bag device mounted in a dashboard. The air bag includes a baffle covering a gas inlet. The baffle controls the flow of gas within the airbag. The gas entering the air bag through the inlet during the initial stage of inflation strikes against the baffle and is divided into a stream of gas flowing forward and a stream of gas flowing backward. The baffle can be formed from only a small amount of material, since it does not have to be of any greatly enlarged length, but has only to be formed with a portion having a concavely curved inner surface facing the gas inlet. Nevertheless, it enables the air bag to extend backwardly along the surface of the dashboard during the initial stage of its inflation.
The cross-sectional area SF of the baffle at the front end is larger than the cross-sectional area SB at the back end. With this arrangement, a stream of inflating gas flowing forward in the bag is larger than a stream of gas flowing backward. This enables the air bag to have a portion protrude from the dashboard and extend backward quickly along a windshield, so that another portion thereof facing the passenger may become upright quickly.